Term for the saline equilibrium of the body?

There is a term for the balanced percentage level of salt in the body, but I can't remember what it is. It is not eutectic, but it is a word like that. The X level of salts in the human body is 0.9%.


The term is isotonic.

Denoting or relating to a solution having the same osmotic pressure as some other solution, especially one in a cell or a body fluid.